PHNOM PENH, Cambodia (AFP) – Cambodia began a roll out of COVID-19 vaccinations for teenagers in its capital Phnom Penh and three provinces Sunday, with Premier Hun Sen's grandchildren among the first to get the jab.

Several countries in Southeast Asia are currently experiencing a deadly COVID-19 resurgence largely driven by the highly contagious Delta variant, which has set back the region's successes last year in curbing pandemic tolls.

While Cambodia appeared to have escaped the brunt of the virus last year, an outbreak first detected in February has steadily driven up the caseload to nearly 78,000.

On Sunday, the kingdom began vaccinating children between the ages of 12 to 17, starting the campaign in its capital Phnom Penh, as well as in the three hardest-hit provinces of Kandal, Koh Kong and Preah Sihanouk.

"The vaccination for children today is a key step to herd immunity in communities," said the Cambodian leader.

"Children are like bamboo shoots. If the health of children is damaged now, we won't have good bamboos."

Earlier in the day, he watched as doctors administered the Chinese-made Sinovac to his grandchildren.

They will be among the two million teenagers expected to be vaccinated, Hun Sen said, adding that the kingdom is mulling inoculating children aged ten and eleven.

Several countries in Europe -- like Denmark, France and Lithuania -- have begun vaccinating children in a bid to faster reach herd immunity.

Cambodia's mass inoculation campaign has so far seen more than seven million people out of the ten million eligible receive the UK-produced AstraZeneca, the US-donated Johnson & Johnson, or the Chinese-made Sinovac and Sinopharm jabs.

Hun Sen said Sunday authorities will also soon begin administering booster shots to adults who are fully vaccinated, and will take a page out of neighboring Thailand's book by mixing vaccines.

In line with this policy, the premier -- who has already received two doses of the AstraZeneca jab -- said he wants to receive a booster shot of Sinovac.

Cambodia has some of the region's weakest healthcare infrastructure and is ill-equipped to deal with a major outbreak of COVID.

On Thursday it imposed fresh restrictions on eight provinces bordering Thailand -- which has seen skyrocketing cases and deaths due to the Delta variant.

Cambodian migrant workers in Thailand have also been barred from returning home.